Laboratory Studies

Urine, blood, or hair testing for specific offending chemicals is expensive and time-consuming, and must be collected immediately after the exposure to obtain reliable results. In many cases the patient may be cured or deceased before results are returned from reference laboratories. Nevertheless, when looking retrospectively at an alleged chemical illness to see if exposure actually occurred or if the illness can be attributed to a specific substance, a blood or urine test for the specific offending chemical can be helpful. Therefore, it is useful to draw an extra tube of blood in the laboratory or emergency department and freeze it for later testing (1,8,9).

Blood, liver, and renal test results may be obscured by a preexisting disease and may be abnormal only in severe exposures. Nevertheless, such tests should be done as soon after the alleged exposure as possible to establish a baseline and to exclude other illnesses such as anemia, diabetes, thyroid disease, and infectious diseases. Rapid drug and alcohol tests can quickly document drug intoxication concomitant with, or masquerading as, a chemical related illness. Cholinesterase testing for organophosphate poisoning is discussed in Chapter 9 (16).